Wireless communication device

ABSTRACT

According to an embodiment, a wireless communication device, which complies with plural communication methods, includes a storing circuit and a received data selection determining circuit. The storing circuit sequentially stores a first received data until the first received data reaches a predetermined data size. When it is assumed that a radio signal complies to a second communication method, a first period is longer than a second period. The first period is a period from a first time when a reception of the radio signal is started to a second time when the first received data with the data size is stored. The second period is a period from the first time to a time when a second reception start signal is detected. The received data selection determining circuit determines a selection of the first received data, when the second reception start signal is not detected at the second time.

CROSS REFERENCE TO RELATED APPLICATION

This is a Continuation of application Ser. No. 14/466,266, filed on Aug.22, 2014, which is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2014-41960 filed on Mar. 4,2014 in Japan, the entire contents of which are incorporated herein byreference.

FIELD

Embodiments described herein relate generally to a wirelesscommunication device.

BACKGROUND

A wireless communication device that performs a short-distance wirelesscommunication in a noncontact manner is known. There is a possibilitythat a reception error may occur depending on the communicationdistance, the state of the antenna, or the characteristic of thedemodulator in the wireless communication device described above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a schematic configuration of a wirelesscommunication device according to a first embodiment.

FIG. 2 is a flowchart describing an operation of the wirelesscommunication device illustrated in FIG. 1.

FIG. 3 is a block diagram of a schematic configuration of a wirelesscommunication device of a first comparative example.

FIG. 4 is a block diagram of a schematic configuration of a wirelesscommunication device according to a second embodiment.

FIG. 5 is a flowchart describing an operation of the wirelesscommunication device in FIG. 4.

FIG. 6 is a block diagram of a schematic configuration of a wirelesscommunication device according to a third embodiment.

FIG. 7 is a block diagram of a schematic configuration of a wirelesscommunication device according to a fourth embodiment.

FIG. 8 is a flowchart describing an operation of the wirelesscommunication device in FIG. 7.

FIG. 9 is a block diagram of a schematic configuration of a wirelesscommunication device of a second comparative example.

DETAILED DESCRIPTION

According to an embodiment, a wireless communication device isconfigured to comply with a plurality of communication methods. Thewireless communication device includes a rectifying circuit, a firstconverting circuit, a second converting circuit, a first reception startsignal detecting circuit, a second reception start signal detectingcircuit, a storing circuit, a received data selection determiningcircuit, and a receiving circuit. The rectifying circuit is configure torectify a radio signal received at an antenna. The first convertingcircuit is configured to sequentially convert an output signal of therectifying circuit into first received data in a conversion process fora first communication method. The second converting circuit isconfigured to sequentially convert the output signal of the rectifyingcircuit into second received data in a conversion process for a secondcommunication method. The first reception start signal detecting circuitis configured to detect a first reception start signal specified in thefirst communication method from the first received data. The secondreception start signal detecting circuit is configured to detect asecond reception start signal specified in the second communicationmethod from the second received data. The second reception start signalis longer and more complicated than the first reception start signal.The storing circuit is configured to sequentially store the firstreceived data until the first received data reaches a predetermined datasize, after the first reception start signal is detected. When it isassumed that the radio signal complies to the second communicationmethod, a first period is equal to or longer than a second period. Thefirst period is a period from a time when a reception of the radiosignal is started to a time when the first received data with the datasize is stored. The second period is a period from a time when areception of the radio signal is started to a time when the secondreception start signal is detected. The received data selectiondetermining circuit is configured to determine a selection of the firstreceived data when the second reception start signal is not detected atthe time the first received data with the data size is stored in thestoring circuit, and determine a selection of the second received datawhen the second reception start signal is detected. The receivingcircuit is configured to receive the first received data or the secondreceived data that is determined in the received data selectiondetermining circuit.

Embodiments will now be explained with reference to the accompanyingdrawings.

First Embodiment

FIG. 1 is a block diagram of a schematic configuration of a wirelesscommunication device 100 according to the first embodiment. The wirelesscommunication device 100 operates in a Card Emulation mode in compliancewith the Near Field Communication (NFC) standard. In other words, thewireless communication device 100 complies with a communication methodof “Type A” (NFC-A) in ISO/IEC 14443 (a first communication method), acommunication method of “Type B” (NFC-B) in ISO/IEC 14443 (a thirdcommunication method), and a communication method of “Type F” (NFC-F) inISO/IEC 18092 (a second communication method).

The communication methods in NFC-A, B and F are also referred to astechnologies. The wireless communication device 100 can be embedded, forexample, in a mobile phone or a smartphone.

As illustrated in FIG. 1, the wireless communication device 100 includesan antenna 1, a capacitor C1, a rectifying circuit 2, a receptiondemodulator 3, a Bit Code Decode circuit 4, a reception start signaldetecting circuit 5, a received data selection determining circuit 6, areceived data selection control circuit 7, a receiving circuit 8, abuffer RAM 9, a small-scale data temporarily storing circuit(hereinafter, referred to as a storing circuit) 10, and a small-scaledata temporary storage control circuit (hereinafter, referred to as astorage control circuit) 11.

An antenna 1 is, for example, a coil and receives a radio signal from anexternal device such as a reader/writer (R/W). The capacitor C1 isconnected to both ends of the antenna 1. The rectifying circuit 2rectifies the radio signal received in the antenna 1. The rectifyingcircuit 2 includes a bridge diode to which four diodes are connected.

The reception demodulator 3 is an analog circuit and includes an NFC-Ademodulator 31, an NFC-B demodulator 32, and an NFC-F demodulator 33.Hereinafter, the NFC-A, B, and F demodulator 31 to 33 may be merelyreferred to as demodulators 31 to 33.

Each of the demodulators 31 to 33 demodulates (binarizes) the outputsignal of the rectifying circuit 2 to output the binarized signal. Eachof the demodulators 31 to 33 is optimized according to thecharacteristic of the technology with which each of the demodulators iscompatible and performs a waveform processing, for example, using afilter according to the technology with which each of the demodulatorsis compatible. In other words, the demodulators 31 to 33 may outputbinarized signals different from each other from the same radio signal.

The bit code decode circuit 4 includes an NFC-A decode circuit 41, anNFC-B decode circuit 42, and an NFC-F decode circuit 43. Hereinafter,the NFC-A, B, and F decode circuits 41 to 43 may be merely referred toas decode circuits 41 to 43. Each of the decode circuits 41 to 43 aredesigned in compliance with the standard of the technology with whicheach of the decode circuits is compatible.

The NFC-A decode circuit 41 decodes the binarized signals from the NFC-Ademodulator 31 to sequentially convert the binarized signals intoreceived data in NFC-A (first received data).

The NFC-B decode circuit 42 decodes the binarized signals from the NFC-Bdemodulator 32 to sequentially convert the binarized signals intoreceived data in NFC-B (third received data).

The NFC-F decode circuit 43 decodes the binarized signals from the NFC-Fdemodulator 33 to sequentially convert the binarized signals intoreceived data in NFC-F (second received data). The received data inNFC-A, B, and F is digital data.

The NFC-A demodulator 31 and the NFC-A decode circuit 41 are included ina first converting circuit. In other words, the first converting circuitsequentially converts the output signal of the rectifying circuit 2 intothe received data in NFC-A in a conversion process for the communicationmethod in NFC-A.

The NFC-F demodulator 33 and the NFC-F decode circuit 43 are included ina second converting circuit. In other words, the second convertingcircuit sequentially converts the output signal of the rectifyingcircuit 2 into the received data in NFC-F in a conversion process forthe communication method in NFC-F.

The NFC-B demodulator 32 and the NFC-B decode circuit 42 are included ina third converting circuit. In other words, the third converting circuitsequentially converts the output signal of the rectifying circuit 2 intothe received data in NFC-B in a conversion process for the communicationmethod in NFC-B.

The reception start signal detecting circuit 5 includes an NFC-Areception start signal (soc) detecting circuit (a first reception startsignal detecting circuit) 51, and an NFC-B reception start signal (soc)detecting circuit (a third reception start signal detecting circuit) 52,and an NFC-F reception start signal (soc) detecting circuit (a secondreception start signal detecting circuit) 53. Hereinafter, the NFC-A, B,and F reception start signal detecting circuits 51 to 53 may be merelyreferred to as reception start signal detecting circuits 51 to 53.

The reception start signal is defined as Start of Communication (soc) inNFC-A, is defined as Start of Frame (sof) in NFC-B, and is defined as apreamble+sync code in NFC-F. In FIG. 1 and FIGS. 3, 4, and 6 that are tobe described below, the “reception start signals” are collectivelyreferred to as the “soc”.

The NFC-A reception start signal detecting circuit 51 detects an NFC-Areception start signal (the first reception start signal) specified inthe communication method in NFC-A from the received data in NFC-A. TheNFC-A reception start signal is a 1-bit “L” (=“0”).

The NFC-B reception start signal detecting circuit 52 detects an NFC-Breception start signal (the third reception start signal) specified inthe communication method in NFC-B from the received data in NFC-B. TheNFC-B reception start signal is a 10 to 11-bit “L”+a 2 to 3-bit “H”(=“1”).

The NFC-F reception start signal detecting circuit 53 detects an NFC-Freception start signal (the second reception start signal) specified inthe communication method in NFC-F from the received data in NFC-F.

The NFC-F reception start signal is a preamble+2 byte fixed data(0×B24D). As described above, the NFC-F reception start signal is longer(has a data size larger) than the NFC-A and NFC-B reception startsignals, and more complicated than the NFC-A and NFC-B reception startsignals.

The storage control circuit 11 controls the storing circuit 10 accordingto the detection information about the reception start signal of each ofthe technologies from the reception start signal detecting circuit 5.The storage control circuit 11 controls the received data selectiondetermining circuit 6 according to the storage result from the storingcircuit 10 and the detection information from the reception start signaldetecting circuit 5.

After detecting the NFC-A reception start signal, the storing circuit 10sequentially stores the received data in NFC-A until it reaches apredetermined data size, according to the control of the storage controlcircuit 11. The storing circuit 10 may store the received data in NFC-Aafter suspending for a one-bit time of the received data after thedetection of the NFC-A reception start signal. After the detection ofthe NFC-B reception start signal, the storing circuit 10 sequentiallystores the received data in NFC-B until the received data in NFC-Breaches the above data size. The storing circuit 10 notifies the storageresult to the storage control circuit 11 when the received data in NFC-Aor B with the above data size is stored.

When the NFC-F reception start signal is not detected at the time thereceived data in NFC-A with the above data size is stored in the storingcircuit 10 according to the control of the storage control circuit 11,the received data selection determining circuit 6 determines theselection of the received data in NFC-A. When determining the selectionof the received data in NFC-A, the received data selection determiningcircuit 6 may stop the operations of the NFC-B and F decode circuits 42and 43, and the NFC-B and F reception start signal detecting circuits 52and 53. This can reduce the power consumption.

When the NFC-F reception start signal is not detected at the time thereceived data in NFC-B with the above data size is stored in the storingcircuit 10, the received data selection determining circuit 6 determinesthe selection of the received data in NFC-B. When determining theselection of the received data in NFC-B, the received data selectiondetermining circuit 6 may stop the operations of the NFC-A and F decodecircuits 41 and 43, and the NFC-A and F reception start signal detectingcircuits 51 and 53.

On the other hand, when the reception start signal in NFC-F is detected,the received data selection determining circuit 6 determines theselection of the received data in NFC-F regardless of whether the NFC-Aor B reception start signal is detected. When determining the selectionof the received data in NFC-F, the received data selection determiningcircuit 6 may stop the operations of the NFC-A and B decode circuits 41and 42, and the NFC-A and B reception start signal detecting circuits 51and 52.

The received data selection control circuit 7 controls the selection ofthe received data in the receiving circuit 8 according to thedetermination result from the received data selection determiningcircuit 6.

The receiving circuit 8 receives the received data in NFC-A, thereceived data in NFC-B, or the received data in NFC-F that is determinedin the received data selection determining circuit 6 through the storingcircuit 10. Specifically, the receiving circuit 8 sequentially holds thedetermined received data in NFC-A, B, or F to output the data perpredetermined unit data size to the buffer RAM 9.

The buffer RAM 9 stores the received data in NFC-A, B, or F from thereceiving circuit 8 per unit data size. In other words, the buffer RAM 9is configured to store the received data in one of the technologies.This can reduce the cost because it is not necessary to provide aplurality of buffer RAMs 9.

Hereinafter, the data size in the storing circuit 10 will be described.When the radio signal in NFC-F is converted into the received data inNFC-A in the NFC-A demodulator 31 and the NFC-A decode circuit 41, thereis a possibility that the NFC-A reception start signal detecting circuit51 may determine that the preamble in NFC-F is not modulated (“H”) anddetermine that the neighborhood of the top of the following fixed datain NFC-F (0×B24D) is “L”. Thus, there is a possibility that the NFC-Areception start signal detecting circuit 51 may mistakenly detect anNFC-A reception start signal.

When the radio signal in NFC-F is converted into the received data inNFC-B in the NFC-B demodulator 32 and the NFC-B decode circuit 42, thereis a possibility that the NFC-B reception start signal detecting circuit52 may determine that the preamble in NFC-F is “L” and determine thatthe neighborhood of the top of the following fixed data in NFC-F is “H”.Thus, there is a possibility that the NFC-B reception start signaldetecting circuit 52 may mistakenly detect an NFC-B reception startsignal.

In the detection errors described above, the timing the NFC-A receptionstart signal is mistakenly detected is almost the same as the timing theNFC-B reception start signal is mistakenly detected because the initialcommunications in NFC-A and B start at a communication speed of 106kbps. The timings are the timing of the neighborhood of the top of thefixed data in NFC-F.

The initial communication in NFC-F starts at a communication speed of212 kbps or 424 kbps. Accordingly, 2-byte fixed data in NFC-F (0×B24D)received at 212 kbps can be received in a period of time correspondingto a period of time in which 1-byte data is received at 106 kbps. The2-byte fixed data received at 424 kbps can be received in a period oftime corresponding to a period of time in which 0.5-byte data isreceived at 106 kbps.

In light of the foregoing, the above data size is preferably seven bitsor more when the received data is stored in NFC-A after suspending for a1-bit time (when the time is adjusted), and is preferably eight bits ormore when the received data is stored in NFC-A without the timeadjustment or when the received data is stored in NFC-B. Hereinafter,for clarification, the description is on the assumption that the abovedata size is one byte.

In other words, when it is assumed that the radio signal complies withNFC-F, a first period and a third period are equal to or longer than asecond period. The first period is the period from the time when thereception of the radio signal is started to the time when the receiveddata in NFC-A with the above data size is stored. The third period isthe period from the time when the reception of the radio signal isstarted to the time when the received data in NFC-B with the above datasize is stored. The second period is the period from the time when thereception of the radio signal is started to the time when the receptionstart signal in NFC-F is detected.

FIG. 2 is a flowchart describing an operation of the wirelesscommunication device 100 illustrated in FIG. 1.

When the wireless communication device 100 start operating, thedemodulators 31 to 33, the decode circuits 41 to 43, and the receptionstart signal detecting circuits 51 to 53 operate so as to receive theradio signal in any technology.

In the state, it is first determined whether the reception start signaldetecting circuit 5 detects an NFC-A or B reception start signal (stepS11). When the reception start signal detecting circuit 5 does notdetect an NFC-A or B reception start signal (No in step S11), it isdetermined whether the reception start signal detecting circuit 5detects an NFC-F reception start signal (step S12).

When the reception start signal detecting circuit 5 does not detect anNFC-F reception start signal (No in step S12), the process returns tostep S11. On the other hand, when the reception start signal detectingcircuit 5 detects an NFC-F reception start signal (Yes in step S12), theprocess goes to step S15 to be described below.

When the reception start signal detecting circuit 5 detects an NFC-A orB reception start signal in step S11 (Yes in step S11), the storingcircuit 10 stores the received data in NFC-A or B of which receptionstart signal is detected (step S13).

Next, it is determined whether the reception start signal detectingcircuit 5 detects an NFC-F reception start signal (step S14). When thereception start signal detecting circuit 5 detects the NFC-F receptionstart signal (Yes in step S14), the receiving circuit 8 receives thereceived data in NFC-F (step S15). Specifically, the receiving circuit 8sequentially holds the received data in NFC-F to output the data perunit data size to the buffer RAM 9. When the reception of the receiveddata is completed, the process is terminated.

On the other hand, when the reception start signal detecting circuit 5does not detect an NFC-F reception start signal in step S14 (No in stepS14), it is determined whether the storing circuit 10 stores one-bytereceived data in NFC-A or B (step S16).

When the storing circuit 10 does not store one-byte received data inNFC-A or B (No in step S16), the process returns to step S13 tocontinuously store the received data in NFC-A or B.

When the storing circuit 10 stores one-byte received data in NFC-A or B(Yes in step S16), the receiving circuit 8 receives the received data inNFC-A or B of which reception start signal is detected (step S17).Specifically, the receiving circuit 8 sequentially holds the 1-bytereceived data in NFC-A or B that is stored in the storing circuit 10,and the converted received data in NFC-A or B following the receiveddata to output the data per unit data size to the buffer RAM 9. When thereception of the received data is completed, the process is terminated.

As described above, according to the present embodiment, after the NFC-Aor B reception start signal is detected, when the NFC-F reception startsignal is not detected at the time the 1-byte received data in NFC-A orB is stored in the storing circuit 10, the received data in NFC-A or Bis received. In other words, when the NFC-A or B reception start signalis detected, the reception of the received data in NFC-A or B is notimmediately started and suspended until the time in which the NFC-Freception start signal may be detected is elapsed. On the other hand,when the NFC-F reception start signal is detected, the reception of thereceived data in NFC-F is immediately started.

Thus, the received data in NFC-F is normally received when an NFC-Freception start signal is detected even after an NFC-F reception startsignal is mistakenly detected as an NFC-A or B reception start signal.An NFC-F reception start signal is less likely to mistakenly be detectedbecause being longer than the NFC-A and B reception start signals andmore complicated than the NFC-A and B reception start signals.

This reduces the possibility that the data is received in a wrongtechnology. This can reduce the possibility of reception error.

In other words, this can implement the operation in a card emulationmode with a high percentage of correct answers at a low cost. This canimprove the stability in the communication in NFC with a mobile phone orsmartphone provided with the wireless communication device 100.

Note that the NFC-A demodulator 31 and NFC-B demodulator 32 can beshared. The shared demodulator is optimized according to thecharacteristics of NFC-A and B. In such a case, the NFC-A decode circuit41 decodes the binarized signals from the shared demodulator andconverts the signals into the received data in NFC-A. The NFC-B decodecircuit 42 decodes the binarized signals from the shared demodulator andconverts the signals into the received data in NFC-B.

First Comparative Example

Hereinafter, a first comparative example will be described in comparisonwith the first embodiment.

FIG. 3 is a block diagram of a schematic configuration of a wirelesscommunication device 100X of the first comparative example. Differentlyfrom the first embodiment, the wireless communication device 100X doesnot include a storing circuit 10 and a storage control circuit 11. Thesame components as in FIG. 1 are denoted with the same reference signsin FIG. 3. Hereinafter, the different points will mainly be described.

A received data selection determining circuit 6X determines theselection of the received data in the technology that the receptionstart signal detecting circuit 5 initially notifies, and notifies thedetermination result to the received data selection control circuit 7.Furthermore, the received data selection determining circuit 6X stopsthe operation of the circuit of which technology is not determined amongdecode circuits 41 to 43 and reception start signal detecting circuits51 to 53.

The wireless communication device 100X of the first comparative exampleas described above has a possibility of mistakenly determining the NFC-Freception start signal as an NFC-A or B reception start signal dependingon the communication distance, the state of an antenna 1 or thecharacteristics of demodulators 31 and 32. The simplicity of the NFC-Aand B reception start signals is likely to cause such a determinationerror. In addition, the NFC-A and B demodulators 31 and 32 may beconfigured to output binarized signals obtained by processing thewaveform of the output signal of the rectifying circuit 2 byrestraining, for example, the frequency component according to thestandards of NFC-A and B. This is likely to cause a determination errorbecause the binarized signal, in which the radio signal in NFC-F isbinarized in the NFC-A and B demodulators 31 and 32, may have a waveformsimilar to the waveform indicating the NFC-A or B reception startsignal.

Furthermore, as described above, the timing at which an NFC-A or Breception start signal is determined is earlier than the timing at whichan NFC-F reception start signal is determined. When an NFC-A or Breception start signal is detected earlier, the NFC-F decode circuit 43and the NFC-F reception start signal detecting circuit 53 stopsoperating. Thus, even if the radio signal in NFC-F is actually received,an NFC-F reception start signal is not detected after a determinationerror occurs. The wrong NFC-A or B demodulator 31 or 32 or the like doesnot obtain correct received data from the radio signal in NFC-F. Thiscauses a reception error.

In the case described above, an answer is not sent back to thereader/writer that sends the radio signal to the wireless communicationdevice 100X. This reduces the percentage of correct answers to thecommands from the reader/writer.

Furthermore, the CPU (not illustrated) checks the validity of thereceived data stored in the buffer RAM 9 and, once confirming that thedata is not valid, discards the received data. This increases the loadon the CPU. Furthermore, the received data is not received while the CPUchecks the validity.

Providing a plurality of buffer RAMs 9 to store the received data in aplurality of technologies can solve the problems described above butincreases the cost drastically.

As described above, the first embodiment can solve such problems.

Second Embodiment

The second embodiment is configured to detect an error in the receiveddata stored in the storing circuit 10 a in addition to the process inthe first embodiment.

FIG. 4 is a block diagram of a schematic configuration of a wirelesscommunication device 100 a according to the second embodiment. The samecomponents as in FIG. 1 are denoted with the same reference signs inFIG. 4. Hereinafter, the different points will mainly be described. Thewireless communication device 100 a further includes an error detectingcircuit 12 in addition to the configuration in FIG. 1.

When detecting an error from the received data in NFC-A or B stored in astoring circuit 10 a, the error detecting circuit 12 causes a receivingcircuit 8 to delete the received data stored in the storing circuit 10 awithout receiving the received data in NFC-A or B and causes a receptionstart signal detecting circuit 5 to detect an NFC-A or B reception startsignal again.

Specifically, when detecting an error, the error detecting circuit 12notifies an error detection result to a storage control circuit 11 a.After receiving the error detection result, the storage control circuit11 a controls a received data selection determining circuit 6 a, thestoring circuit 10 a, and the reception start signal detecting circuit5.

The error can be detected under any condition. However, in the presentembodiment, the error detecting circuit 12 detects an error when thereceived data in NFC-A or B stored in the storing circuit 10 a does notcorrespond to an expected value.

The expected value is not especially limited. For example, the followingexpected values can be used. In NFC-A and B, the command to be receivedafter the reception start signal can be limited. The command is “REQA”or “WUPA” in NFC-A, “REQB” or “WUPB” in NFC-B. Accordingly, the expectedvalue is 0×26, 0×52, or 0×35 corresponding to the commands in NFC-A, andis 0×05 in NFC-B. The expected values have seven bits or eight bits.

FIG. 5 is a flowchart describing the operation of the wirelesscommunication device 100 a in FIG. 4. The same components as in FIG. 2are denoted with the same reference signs in FIG. 5. Hereinafter, thedifferent points will mainly be described.

The processes in steps S11 to 16 are the same as in the firstembodiment.

When the storing circuit 10 a stores 1-byte received data in NFC-A or B(Yes in step S16), the error detecting circuit 12 determines whether thereceived data in NFC-A or B stored in the storing circuit 10 acorresponds to the expected value (step S16 a).

When the data corresponds to the expected value (Yes in step S16 a), thereceiving circuit 8 receives the received data in NFC-A or B of whichreception start signal is detected (step S17).

When the data does not correspond to the expected value (No in step S16a), the process returns to step S11.

As described above, in addition to the process in the first embodiment,the present embodiment is configured to detect an NFC-A or B receptionstart signal again when an error is detected from the received data inNFC-A or B stored in the storing circuit 10 a. This further reduces thepossibility of receiving the data in a wrong technology in comparisonwith the first embodiment and can further reduce the possibility ofreception error.

Note that the error detecting circuit 12 can detect an error, forexample, when detecting a reception end signal (eoc: End ofCommunication) before the storage of the received data with apredetermined data size is completed. The reception end signal is, forexample, continuous signals “L”. In the case described above, thereceived data may not reach one byte. When detecting an error, the errordetecting circuit 12 can cause the storing circuit 10 a to delete thestored received data and to suspend the storage of the received data.The error detecting circuit 12 can also detect an error from thereceived data in NFC-A or B that is from a decode circuit 4 and that isnot stored in the storing circuit 10 a.

The error detecting circuit 12 can also detect an error, for example,when a radio signal with a waveform indicating bit coding different fromeach of the technologies is input to the reception demodulator 3. Inother words, as described above, the condition for detecting an error isnot limited to the mismatch between the data and the expected value orthe detection of a reception end signal.

Setting the data size at a size larger than one byte can improve theaccuracy of detection of errors.

Third Embodiment

The second embodiment receives the received data in NFC-A or B when aperiod in which an NFC-F reception start signal is likely to be detectedelapses and an error is not detected. However, differently from thesecond embodiment, the third embodiment does not wait for the elapse ofthe period in which an NFC-F reception start signal is likely to bedetected.

FIG. 6 is a block diagram of a schematic configuration of a wirelesscommunication device 100 b according to the third embodiment. The samecomponents as in FIG. 4 are denoted with the same reference signs inFIG. 6. Hereinafter, the different points will mainly be described.

The data size of the received data stored in the storing circuit 10 bsatisfies the following condition. In other words, on the assumptionthat the radio signal complies with NFC-F, a first period and a thirdperiod are shorter than a second period. The first period is the periodfrom the time when the reception of the radio signal is started to thetime when the received data in NFC-A with the above data size is stored.The third period is the period from the time when the reception of theradio signal is started to the time when the received data in NFC-B withthe above data size is stored. The second period is the period from thetime when the reception of the radio signal is started to the time whenan NFC-F reception start signal is detected.

The data size described above is, for example, less than one byte. Whenthe data size is equal to or more than one byte, the same process as inthe second embodiment is performed.

The error detecting circuit 12 detects an error from the received datain NFC-A or B stored in the storing circuit 10 b. The method ofdetecting an error is the same as in the second embodiment. However,when an expected value is used, an expected value with less than onebyte is used.

A received data selection determining circuit 6 b determines theselection of the received data in NFC-A when the error detecting circuit12 does not detect an error at the time the received data in NFC-A withthe above data size is stored in the storing circuit 10 b.

Furthermore, the received data selection determining circuit 6 bdetermines the selection of the received data in NFC-B when the errordetecting circuit 12 does not detect an error at the time the receiveddata in NFC-B with the above data size is stored in the storing circuit10 b.

Alternatively, the received data selection determining circuit 6 bdetermines the selection of the received data in NFC-F when an NFC-Freception start signal is detected.

When detecting an error, the error detecting circuit 12 causes thereceiving circuit 8 to delete the received data stored in the storingcircuit 10 b without receiving the received data in NFC-A or B andcauses the reception start signal detecting circuit 5 to detect an NFC-Aor B reception start signal again.

Specifically, when detecting an error, the error detecting circuit 12notifies an error detection result to the storage control circuit 11 b.After receiving the error detection result, the storage control circuit11 b controls the storing circuit 10 b, and the reception start signaldetecting circuit 5.

The present embodiment is configured to detect an error of the receiveddata without immediately starting the reception of the received data inNFC-A or B when an NFC-A or B reception start signal is detected. On theother hand, the present embodiment immediately receives the receiveddata in NFC-F when an NFC-F reception start signal is detected.

This can prevent the reception of the received data in NFC-A or B whenan NFC-A or B reception start signal is mistakenly detected and an erroris detected from the received data. After that, when an NFC-F receptionstart signal is detected, the received data in NFC-F can normally bereceived.

This reduces the possibility that the data is received in a wrongtechnology. This can reduce the possibility of reception error.

Fourth Embodiment

The fourth embodiment relates to a wireless communication device 100 cin which a receivable technology is determined in advance.

FIG. 7 is a block diagram of a schematic configuration of a wirelesscommunication device 100 c according to the fourth embodiment. The samecomponents as in FIG. 1 are denoted with the same reference signs inFIG. 7. Hereinafter, the different points will mainly be described.

In the present embodiment, an example in which the wirelesscommunication device 100 c complies with NFC-A will be described.However, the wireless communication device 100 c may comply with NFC-B.The wireless communication device 100 c described above is also referredto, for example, as a non-contact IC card, or an RF-IC CARD.

A reception demodulator 3 c demodulates the output signal of arectifying circuit 2 to output binarized signals. A bit code decodecircuit 4 c decodes the binarized signals from the reception demodulator3 c to convert the signals into the received data in NFC-A. Thereception demodulator 3 c and the bit code decode circuit 4 c areoptimized according to the characteristic of NFC-A. The receptiondemodulator 3 c and the bit code decode circuit 4 c are constituted as aconverting circuit. In other words, the converting circuit sequentiallyconverts the output signal of the rectifying circuit 2 into the receiveddata in NFC-A in a conversion process for the communication method inNFC-A.

The reception start signal detecting circuit 5 c detects a predeterminedNFC-A reception start signal from the received data in NFC-A andnotifies the detection information to the storing circuit 10 c.

After the NFC-A reception start signal is detected, the storing circuit10 c sequentially stores the received data in NFC-A until the datareaches a predetermined data size. In the case described above, the datasize is one byte. However, the data size can be less than one byte orlarger than one byte.

An error detecting circuit 12 detects an error from the received datastored in the storing circuit 10 c. In the present embodiment, the errordetecting circuit 12 detects an error when the one-byte received datastored in the storing circuit 10 c does not correspond to an expectedvalue.

When detecting an error, the error detecting circuit 12 prevents areceiving circuit 8 c from receiving the received data, causes thestoring circuit 10 c to delete the received data stored and causes thereception start signal detecting circuit 5 c to detect the receptionstart signal again.

Specifically, the storage control circuit 11 c controls the receptionstart signal detecting circuit 5 c and the reception control circuit 7 caccording to the error detection result from the error detecting circuit12.

The receiving circuit 8 c receives the received data in NFC-A accordingto the control of the reception control circuit 7 c, when the errordetecting circuit 12 does not detect an error at the time the receiveddata with the above data size is stored in the storing circuit 10 c.

FIG. 8 is a flowchart describing the operation of the wirelesscommunication device in FIG. 7.

First, it is determined whether the reception start signal detectingcircuit 5 c detects an NFC-A reception start signal (step S41). When thereception start signal detecting circuit 5 c does not detect thereception start signal (No in step S41), the process returns to stepS41.

When the reception start signal detecting circuit 5 c detects thereception start signal (Yes in step S41), the storing circuit 10 cstores the received data in NFC-A (step S42).

It is determined whether the storing circuit 10 c stores one-bytereceived data (step S43). When the storing circuit 10 c does not storeone-byte received data (No in step S43), the process returns to stepS42.

When the storing circuit 10 c stores one-byte received data (Yes in stepS43), the error detecting circuit 12 determines whether the receiveddata stored in the storing circuit 10 c corresponds to the expectedvalue (step S44).

When the stored received data corresponds to the expected value (Yes instep S44), the receiving circuit 8 c receives the received data (stepS45). Specifically, the receiving circuit 8 c sequentially holds theone-byte received data stored in the storing circuit 10 c and thereceived data following the received data to output the data per unitdata size to a buffer RAM 9.

On the other hand, when the stored received data does not correspond tothe expected value (No in step S44), the process returns to step S41. Asan example of the case described above, in which a radio signal in NFC-For a noise is received can be cited.

As described above, the present embodiment is configured to receive thereceived data when the error detecting circuit 12 does not detect anerror at the time the received data stored in the storing circuit 10 creaches one byte after the reception start signal is detected. This canreduce the possibility of reception error because merely detecting areception start signal is not enough to receive the received data.

Note that, as described in the second embodiment, the error detectingcircuit 12 may detect an error, for example, when detecting a receptionend signal.

Second Comparative Example

Hereinafter, the second comparative example will be described incomparison with the fourth embodiment.

FIG. 9 is a block diagram of a schematic configuration of a wirelesscommunication device 100Y of the second comparative example. Differentlyfrom the fourth embodiment, the wireless communication device 100Y doesnot include a storing circuit 10 c, a storage control circuit 11 c, andan error detecting circuit 12. The same components as in FIG. 7 aredenoted with the same reference signs in FIG. 9. Hereinafter, thedifferent points will mainly be described.

When a reception start signal detecting circuit 5 c detects an NFC-Areception start signal, a reception control circuit 7 c immediatelycauses a receiving circuit 8 c to receive the received data.

The wireless communication device 100Y of the second comparative exampleas described above has a possibility of mistakenly determining an NFC-Freception start signal or a noise as the NFC-A reception start signaldepending on the communication distance, the state of an antenna 1 orthe characteristic of a reception demodulator 3 c. This causes areception error because correct received data is not obtained. Thiscauses a problem, for example, of the increase in the load of the CPU,similarly to the first comparative example. As described above, thefourth embodiment can solve such a problem.

At least a portion of the wireless communication device described in theabove embodiments may be constituted by hardware or software. In thesoftware configuration, a program realizing at least a portion of thefunctions of the wireless communication device is stored in a recordingmedium such as a flexible disk or a CD-ROM and may be read by a computerto be executed thereby. The storage medium is not limited to adetachable one such as a magnetic disk and an optical disk and may be astationary recording medium such as a hard disk device and a memory.

Furthermore, the program realizing at least a portion of the wirelesscommunication device may be distributed through a communication line(including wireless communication) such as the Internet. While theprogram is encrypted, modulated, or compressed, the program may bedistributed through a wired line or a wireless line such as theInternet, or the program stored in a recording medium may bedistributed.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel methods and systems describedherein may be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the methods andsystems described herein may be made without departing from the spiritof the inventions. The accompanying claims and their equivalents areintended to cover such forms or modifications as would fall within thescope and spirit of the inventions.

The invention claimed is:
 1. A wireless communication device comprising:a first converting circuit configured to decode a signal inputted froman external using a first communication method and to generate firstreceived data; a second converting circuit configured to decode a signalinputted from the external using a second communication method and togenerate second received data; a first reception start signal detectingcircuit configured to receive the first received data and to detect afirst reception start signal specified in the first communicationmethod; a second reception start signal detecting circuit configured toreceive the second received data and to detect a second reception startsignal specified in the second communication method; a storing circuitconfigured to store the first received data in response to detectioninformation outputted from the first reception start signal detectingcircuit; a received data selection determining circuit configured todetermine a selection of the second received data only when the secondreception start signal detecting circuit outputs detection information;a receiving circuit configured to receive the first received data, thatis outputted from the storing circuit, or the second received data. 2.The wireless communication device according to claim 1, furthercomprising: an error detecting circuit configured to detect an error inthe first received data.
 3. The wireless communication device accordingto claim 2, wherein the first reception start signal detecting circuitdetects the first reception start signal again in response to errordetection signal outputted from the error detecting circuit.
 4. Thewireless communication device according to claim 2, wherein the errordetecting circuit compares the first received data with an expectedvalue.
 5. The wireless communication device according to claim 2,wherein the error detecting circuit compares the first received datawith a reception end signal.
 6. The wireless communication deviceaccording to claim 1, wherein the received data selection determiningcircuit stops an operation of the first reception start signal detectingcircuit when determining a selection of the second received data.
 7. Thewireless communication device according to claim 6, wherein the storingcircuit stores the first received data until the first received datareaches a predetermined data size.
 8. The wireless communication deviceaccording to claim 7, wherein the first communication method is acommunication method of Type A in ISO/IEC 14443, the secondcommunication method is a communication method of Type F in ISO/IEC18092, the data size is equal to or more than seven bits, and the secondreception start signal is longer and more complicated than the firstreception start signal.
 9. A wireless communication device comprising: afirst converting circuit configured to decode a signal inputted from anexternal using a first communication method and to generate firstreceived data; a second converting circuit configured to decode a signalinputted from the external using a second communication method and togenerate second received data; a third converting circuit configured todecode a signal inputted from the external using a third communicationmethod and to generate third received data; a first reception startsignal detecting circuit configured to receive the first received dataand to detect a first reception start signal specified in the firstcommunication method; a second reception start signal detecting circuitconfigured to receive the second received data and to detect a secondreception start signal specified in the second communication method; athird reception start signal detecting circuit configured to receive thethird received data and to detect a third reception start signalspecified in the third communication method; a storing circuitconfigured to store the first received data or the third received datain response to detection information outputted from the first receptionstart signal detecting circuit or in response to detection informationoutputted from the third reception start signal detecting circuit; areceived data selection determining circuit configured to determine aselection of the second received data only when the second receptionstart signal detecting circuit outputs detection information; areceiving circuit configured to receive any one of the first receiveddata, that is outputted from the storing circuit, the third receiveddata, that is outputted from the storing circuit, or the second receiveddata.
 10. The wireless communication device according to claim 9,further comprising: an error detecting circuit configured to detect anerror in the first received data or the second received data.
 11. Thewireless communication device according to claim 10, wherein the firstand third reception start signal detecting circuits respectively detectthe first and third reception start signals again in response to errordetection signal outputted from the error detecting circuit.
 12. Thewireless communication device according to claim 10, wherein the errordetecting circuit compares the first received data with a first expectedvalue and compares the third received data with a second expected value.13. The wireless communication device according to claim 10, wherein theerror detecting circuit compares the first received data with a firstreception end signal and compares the third received data with a secondreception end signal.
 14. The wireless communication device according toclaim 13, wherein the first expected value is 0×26, 0×52, or 0×35corresponding to the commands in NFC-A, the second expected value is0×05 corresponding to the commands in NFC-B.
 15. The wirelesscommunication device according to claim 9, wherein the received dataselection determining circuit stops an operation of the first and thirdreception start signal detecting circuits when determining a selectionof the second received data.
 16. The wireless communication deviceaccording to claim 15, Wherein the storing circuit stores the firstreceived data until the first received data reaches a predetermined datasize.
 17. The wireless communication device according to claim 16,wherein the first communication method is a communication method of TypeA in ISO/IEC 14443, the second communication method is a communicationmethod of Type F in ISO/IEC 18092, the third communication method is acommunication method of Type B in ISO/IEC 14443, the data size is equalto or more than seven bits, and the second reception start signal islonger and more complicated than the first reception start signal.
 18. Awireless communication device comprising: a converting circuitconfigured to decode a signal inputted from an external and to generatereceived data; a reception start signal detecting circuit configured toreceive the received data and to detect a predetermined reception startsignal; a storing circuit configured to store the received data untilthe received data reaches a predetermined data size in response todetection information outputted from the reception start signaldetecting circuit; an error detecting circuit configured to detect anerror in the received data; a receiving circuit configured to receivethe received data in response to the error that is detected by the errordetecting circuit wherein, when the error detecting circuit does notdetect an error at the time the received data with the data size isstored in the storing circuit, the receiving circuit receives thereceived data, and when detecting an error, the error detecting circuitprevents the receiving circuit from receiving the received data.
 19. Thewireless communication device according to claim 18, wherein the errordetecting circuit detects an error when the received data stored in thestoring circuit does not correspond to an expected value.
 20. Thewireless communication device according to claim 19, wherein the storingcircuit stores the received data until the received data reaches apredetermined data size, the data size is equal to or more than sevenbits, the wireless communication device uses a communication method ofType A or Type B in ISO/IEC 14443.